Nickel zinc copper ferrite for VUHF antenna application

Abstract

A composition and a solid material is especially suitable for the manufacture of an antenna adapted to operate in the very high frequency and ultra high frequency or V/UHF band. The composition has the formula NiaZnbCucCodFe2−δO4, in which 2(a+b+c+d)+3(2−δ)=8, 0.05<b<0.5, e.g. 0.1<b<0.5, e.g. 0.1<b<0.4, e.g. 0.15<b<0.35, 0.10<c<0.25, preferably 0.15<c<0.25, alternatively c is 0.20, 0.04<d<0.25, preferably 0.06<d<0.25, and more preferably 0.07<d<0.25, and δ<0.05.

What is claimed is: 
     
       1. A composition chosen from compositions of the following formulas:
   Ni 0.4805 Zn 0.3195 Cu 0.20 Co 0.06 Fe 1.96 O 4 , 
   Ni 0.4405 Zn 0.3195 Cu 0.20 Co 0.10 Fe 1.96 O 4 , 
   Ni 0.4347 Zn 0.3153 Cu 0.20 Co 0.11 Fe 1.96 O 4 , 
   Ni 0.4231 Zn 0.3069 Cu 0.20 Co 0.13 Fe 1.96 O 4 , 
   Ni 0.4115 Zn 0.2985 Cu 0.20 Co 0.15 Fe 1.96 O 4 ; and 
   Ni 0.6 Zn 0.2 Cu 0.20 Co 0.06 Fe 1.96 O 4 . 
 
     
     
       2. The composition of  claim 1 , forming a magneto-dielectric material. 
     
     
       3. The composition of  claim 1 , wherein it has a magnetic permeability μ′ of 10 to 20 for the VHF range (1 MHz to 300 MHZ) or μ′ of 5 to 15 for the V/UHF range (200 MHZ to 600 MHZ). 
     
     
       4. The composition according to  claim 1 , wherein it has magnetic losses tan (δ u )<0.06 over the frequency band between 100 and 200 MHZ, measured between 1 MHz and 1 GHZ. 
     
     
       5. The composition of  claim 1 , having a magnetic permeability μ′>1 and a dielectric permittivity ε′>1 over the frequency band between 100 and 200 MHZ, measured between 1 MHz and 1 GHZ. 
     
     
       6. The composition of  claim 1 , wherein μ′≥5 and ε′≥10 over the frequency band between 100 and 200 MHZ, measured between 1 MHz and 1 GHz. 
     
     
       7. The composition according to  claim 1 , wherein the dielectric losses tan(δ√) is <0.02 over the frequency band between 100 and 200 MHz, measured between 1 MHz and 1 GHZ. 
     
     
       8. A VHF or V/UHF antenna wherein it comprises a composition of the formula Ni a Zn b Cu c Co d Fe 2−δ O 4 , wherein:
 2(a+b+c+d)+3(2−δ)=8 
 0.05<b<0.5, 
 0.10<c<0.25, 
 0.04<d<0.25, and 
 δ<0.05. 
 
     
     
       9. The VHF or V/UHF antenna according to  claim 8 , wherein it has a larger dimension of less than 300 mm. 
     
     
       10. A VHF or V/UHF antenna of the printed or microstrip type, wherein it comprises one or more layers of a substrate bonded to a radiating element, of which one or more layers of the substrate comprises a composition of the formula Ni a Zn b Cu c Co d Fe 2−δ O 4 , wherein:
 2(a+b+c+d)+3(2−δ)=8 
 0.05<b<0.5, 
 0.10<c<0.25, 
 0.04<d<0.25, and 
 δ<0.05. 
 
     
     
       11. A method for manufacturing a composition according to  claim 1 , characterised in that wherein said method comprises:
 grinding raw materials providing Ni, Zn, Cu, Co, Fe and O to obtain a powder, after grinding, the powder is dried and then sieved, 
 after sieving, the powder is heat-treated at a temperature of at least 600° C. for 1 to 10 hours, 
 after heat treatment, the powder undergoes a second grinding, and 
 then the powder is shaped into a solid material. 
 
     
     
       12. The method according to  claim 11 , wherein prior to shaping, the method comprises coating the powder with a binder. 
     
     
       13. The method according to  claim 11 , wherein after shaping, the method comprises sintering the solid material. 
     
     
       14. The method according to  claim 11 , wherein the raw materials providing Ni, Zn, Cu, Co, Fe and O are NiO; ZnO; CuO; Co 3 O 4  and Fe 2 O 3 .